Re: [PATCH v3 0/9] x86,fs/resctrl: Fix long-standing issues

[Luck, Tony]

On Fri, May 22, 2026 at 12:15:04PM -0700, Reinette Chatre wrote:
> v2: https://lore.kernel.org/lkml/20260515193944.15114-1-tony.luck@xxxxxxxxx/
> v1: https://lore.kernel.org/all/20260508182143.14592-1-tony.luck@xxxxxxxxx/
> 
> While reviewing the AET series [1] Sashiko reported a deadlock during mount,
> and a use-after-free when an L3 domain is removed during CPU offline. Reinette
> found a memory leak in the mount error path while refactoring code for a
> solution to the mount hang.
> 
> During review of V1 of this series Sashiko found a new UAF on unmount issue
> that was fixed in V2.
> 
> During review of V2 Sashiko uncovered a couple more new issues: TOCTOU
> involving rdtgroup_kn_put() that may lead to UAF or double-free, double
> free of pseudo-locked regions, potential deadlock between resctrl unmount and
> info file readers. Sashiko also found that the CPU offline fix in V2 is flawed
> in its use of is_percpu_thread().
> 
> Address all issues identified. This version is significantly different from V2
> because of the additional fixes and reworking of the CPU offline fix. I do not
> consider this version quite "polished" but after all changes made to address
> all the issues identified by Sashiko I would like to check-in with folks (and
> Sashiko) on where the fixes are headed and would appreciate any feedback.

Several of these patches are either authored or co-authored by me, so
I'm uncertain about the ethics of piling on a Reviewed-by tag.

Apart from patch 6 to fix sashiko reported issues in pseudo-locking
everything looks good. I agree with Reinette's assessment[1] that
pursuing the bizarre corner case races for pseudo-locking should
not be a priority. That patch can be dropped.

-Tony

[1] https://lore.kernel.org/all/e40a924f-5398-43bd-821a-2ff9873c5a4c@xxxxxxxxx/